Electrolytic apparatus.



W. E. GREENAWALT.

ELECTROLYTIC APPARATUS. APPL lCAT|0N FILED JUNE 30.1913.

Patnted June 20, 1916.

THU 3 THE 2 WILLIAM E. GREENAWALT, 0F DENVER, COLORADO.

ELECTROLYTIC APPARATUS.

LTWWQWT.

Specification of Letters JPatent.

Patented time so, rare.

Application filed June 30, 1913. Serial No. 776,485.

To all whom it may concern:

Be it known'that I, WILLIAM E. GREENA- WALT, a citizen of the UnitedStates, residing in the city and county of Denver and State of Colorado,have invented certain new and useful Improvements in ElectrolyticApparatus.

It has for its more immediate objects the more ei'ficient application ofthe current by adequately agitating'the electrolyte, retarding thedisintegration of the electrodes, maintaining the electrodes free fromhydrogen or other polarizing gases, and maintaining the apparatus incontinuous operation for extended periods.

The apparatus may be successfully used in the electro deposition ofcopper from sulfate solutions with insoluble anodes, in the electrolysisof copper matte, copper sulfid precipitate, cement copper, zinc oxid,zinc sulfate, copper oxid, lead sulfate, lead sulfid, and the depositionof gold and silver from cyanid solutions, as well as numerous other useswhich will be evident to any one skilled in the art.

One ofthe most interesting, as well as one of the most diiiicultproblems in electrometallurgy has been the deposition of copper fromsulfate solutions, with insoluble anodes, and this problem hashitherto'defled all attempts at successful solution ona commercial orpracticable basis.

The principal difficulties which have hitherto militated againstsuccessful electrolysis of impure copper sulfate solutions are fairlywell understood, but among these maybe mentioned; first, the rapiddisintegration of the insoluble anode with all of its attendant evils;second, inefficiency of the electrolysis due to fouling of theelectrolyte; third, inability to build up the cathode to a suitablethickness except at very small current densities; fourth, polarization,which makes it impracticable to use reasonably high working currentdensities.

lif an attempt is made at the ordinary electrolysis of impure coppersulfate solutions, as those obtained in leaching copper ores, with leadanodes, the lead is disintegrated at the rate of about 12 ounces, perpound of copper deposited. The peroxid of lead so formed increases theresistance, and consequently the power, short circuits the current bydropping from time to time to the bottom of the electrolyzer and comingin contact with the cathode. It is expensive material.

to frequently renew the lead anodes and to frequently remove theperoxid. And so far, no more suitable anode than lead, for sulfatesolutions, has yet been discovered.

The principal result of the fouling of the electrolyte is currentinefficiency, due to useless oxidation and reduction. One of theunavoidable results of treating copper ores with a sulfate solution isthe soluble iron. This iron, in the ferrous condition, is quiteharmless, but under the action of electrolysis, the ferrous iron isconverted into the ferric iron at the anode, and finding its way back tothe cathode, is again reduced to ferrous iron at the expense of thedeposited copper, thus resulting ina loss of efficiency. This may becomeso aggravated, that under certain conditions no copper will bedeposited.

The diiiicultiesat the cathode are no less than those at the anode.Except for exceedingly low current densities the deposited copper isquite irregular, and unless closely watched, trees and nodule will buildout to the anode, ultimately short circuiting the current, and thustemporarily throwing the electrolyzer out of commission until thedifficulty is repaired. If the deposited metal is loose, spongy orgranular, as will be the case with foul and almost neutral solutions orwith moderately high current densities,

the copper falling to the bottom of the elec trolyzer mixes with thedisintegrated anode The separation of this mixture offers an additionalmetallurgical difliculty. Polarizing gases, except for very low currentdensities, are a matter of concern in the deposition of metals withinsoluble anodes. Merely circulating the electrolyte, no matter howrapidly, does not satisfactorily overcome the trouble, and for highcurrent densities, is entirely useless. in my apparatus all thesedifficulties are successfully surmounted,

as will now be described in detail, having in mind, more particularly,the electrolysis of impure copper sulfate solutions obtained fromleaching copper ores.

-Referring to the accompanying drawings, Figure 1 represents alongitudinal section through the apparatus, and Fig. 2: thecorresponding transverse section. Fig. 4 represents a longitudinalsection through amodified apparatus, and Fig. 3 the corre spondingtransverse section. Fig. 5 represents an enlarged section through oneend of the anode bell.

- v 16 and 17 into the bottom and is absorbed by the solution. Iflead-anode'sare used the In the figures, 1 represents an electrolytetank, containing the electrolyte and substantially horizontal cathode 2.

3 represents an anode bell containing the anolyte and-substantiallyhorizontal anodes 4:, and having, preferably, a diaphragm 5, interposedbetween the electrodes, and attached to the anode bell, thus separatingthe anolyte from the catholyte.

The anode bell is suspended by hangers 6, so that it may be oscillated,preferably from fixed pivotal points, when actuated by the mechanism 7.Faucet 8 serves to'introduce 'the catholyte into the apparatus, and thepipe 10 serves to Withdraw it. Faucet 9 serves to introduce the anolyteinto the apparatus and the flexible tubin 11 serves to withdraw it. Thistubing is exible and is immersed in the catholyte, it is fastened to theanode bell, passes through the catholyte and sides of the cathode tank,so that the anolyte may flow out unimpeded, While the anode bell is inoscillation, and without mingling with the catholyte. This prevents theferric iron at the anode from gettingto the cathode and thus reducingthe current efficiency. The degree of this efficiency will depend mostlyon the nature of the dia- 'phragm; if the diaphragm is dense, so thatlittle or no diffusion takes place, none of the ferric iron orregenerated acid in the anode compartment finds its way back to thecathode, and hence the current efficiency closely approximates 100 percent. If the diaphragm permits of more or less diffusion, the efficiencywill still be .quite good provided that the'impurities in the solutionare not great. If the electrolyte is reasonably pure a diaphragm of lowelectrical resistance is preferred. In any event, the outlet for theelectrolyte is preferably through the flexible "tubing 11, rather thanfrom the catholyte outlet 10.

It will usually be found desirable to introducea reagent into either theanolyte, the catholyte, or both. In such a case'the solution is'preferably sprayed into towers 14:.

and 15, through the sprayers 12 and 13, while the reducing agent, as forexample sulfur'dioxid, is forced through the pipes introduction ofsulfur dioxid into the electrolyte, in addition to acting as adepolarizer, acts as an acid generator, and also tends to loosen thedisintegrated anode material from the face of the anode, and thus,revent the excessive rise in voltage required for the continuousoperation of the apparatus and carrying out of the process. The

loosening of the disintegrated or non-adherent electrode material mayalso be facilitated by simultaneously applying a small alternatingcurrent, in connection with the direct current, as illustrated in Fig.4. The

accomplished,necessitates the dismantling of the cell. In the presentinvention the apparatus is arranged to make its removal from the sphereof influence of the electric current continuous and automatic, and togreatly facilitate its removal without dismantling the electrolyzer.

If the non-adherent electrode material is intensely fine and readilyheld in suspension the simple oscillating action of the diaphragm andcirculation of the electrolyte will facilitate or cause its removal fromthe sphere of influence of the current. If however, the disintegrated ornon-adherent electrode material is rather heavy, coarse or granular, itsremoval from the sphere of influence of the current is facilitated oraccomplished by giving to the oscillating or moving diaphragm adifferential motion, somewhat similar to that in ordinary concentratingtables, which movement is well known. To best accomplish this the speedof the. movement one way is more rapid or different than the speed ofthe return movement; or, as I have designated it, a differential motion.mitted by the driving belt; in Fig. 4 by the spring or togglearrangement 36. A bumper or spring 45 will answer the same purpose butnot so well.-' This differential motion causes an advance of theinsoluble and nonadherent electrode particles toward one end of thediaphragm or electrolyzer, which may then be removed automatically andcontinuously through theducts 11 or 10, or if too heavy to be .removedwith the electrolyte, they may be removed by hand from time to time fromaccumulations at the end of the apparatus. These accumulations however,at the end of the apparatus, are not affected by the current nor do theyinterfere with its operation. 7

In order to further facilitate the advance movement of the insolubleelectrode Jarticles, it will usually be desirable to s ant thecrossieces of the diaphragm, as shown at 39, wh lethe other ortions ofthe cross- In Fig. 1, it may be transmenace phragm advances theinsoluble particles over the slanting cross-piece, while a slowerretrograde movement does not perceptibly displace it in the oppositedirection, due both to the slower movement and vertical side. Either ofthese methods, the agitation of the particles in the electrolyte, thedifferential movement of the diaphragm or anode bell, or the variationin the shape of the diaphragm cross-pieces, may be used individually orcollectively, depending upon the conditions and the nature of thenonadherent electrode material to be removed. The results obtained bythis apparatus are somewhat surprising. In the ordinary electrolysis ofimpure copper sulfate solutions, by circulating the electrolyte, it hasbeen demonstrated by careful tests that about 0.8 lb. of lead isperoxidized for every pound of copper deposited. This amounts to about1600 pounds of lead, per ton of copper. By using the apparatus hereindescribed, this has been reduced to the phenomenally low amount of 40pounds of lead peroxidized, per ton of copper deposited, in theordinary. process of Working the electrolyzer; that is to say with theordinary rate of oscillation and a current density of 30 amperes persquare foot. On special tests, such for example with a current densityof 100 amperes per square foot, the disintegration ol the lead has beenreduced to even as low as 20 pounds, per ton of copper. It is nowfurther proposed to remove even this small amount of peroxidautomatically, so that the electrolyzer can be operated indefinitelyWithout any difiiculty from the disintegration of the anode, or from anynon-adherent electrode material.

it has been further observed in the oper-- ation ot' this apparatus,that abnormally large current densities can be used without detrimentalresults, or loss of elliciency. Tests with a current of 1000 amperes,and a current density of 104E amperes per square foot show an efliciencyof about 99 per cent. with no evolution of hydrogen at the cathode, Inthe ordinary electrolysis 'using stationary electrodes and a circulatingelectrolyte, with insoluble anodes, a current density of even 10 amperesper square foot is hardly ever free from hydrogen at the oathode and itsattendant evils. However, gases such as air, or hydrogen it developed,may

become entrained by the diaphragm, and

thus have a deleterious influence, especially in increasing theelectrical resistance. To avoid this, means of escape of the gases, suchas anger holes, grooves or sawcuts, are provided in the frame on theunder side of the diaphragrm'as shown at 451, by means of which thegases areat once released and otler no trouble. The movement of thediaphragm oranode bell greatly expedites the removal of such gases.

The high eficiency and results described are largely due to theagitation of the elec trolyte at both electrodes, either with, orwithout a diaphragm. The reactions at the electrodes are greatlyfacilitated, and polarization almost entirely eliminated, thusincreasing the current efficiency at the cathode and greatly decreasingthe rate of disinte gration of the anode.

ln any commercial electrolytic apparatus, especially in a cell having adiaphragm, it has always been inconvenient and quite expensive todismantle the electrolyzer, so that the deposited metal can beremovedand the apparatus easily inspected. This difiiculty is entirelyovercome by the arrangement shown in the drawings. The diaphragm issupported by flexible suspenders (l, attached to a beam 21. The anodesare suspended independently of the diaphragm or anode bell by the rods18, Fig. 1, from the beam 22, which preferably rests on the beams 21,underneath, and which, in turn, may be supported by uprights .20,alongside of the cell. Both 21 and 22 have suitable eye-bolts 2 1T and23, by which the beams 21 and 22 may be elevated simultaneously orseparately. say, by an overhead traveler, taking either, or both, thediaphragm and anode with them.

If, for example, the copper has accunur latcd sulliciently to make itsremoval desirable. it is quickly accomplished by disconnecting theactuating mechanism 7 and the electrical conductors 40, and then bymeans of an over-head hoist attached to the eyebolts 2%, the beams 21and cross-beams 22, together with the diaphragm and anodes are alllifted up together to the height desired for conveniently removing thecopper. The deposited copper may be fine, granular, or reguline, ineither case it is easily removed from the electrolyte tank, and thesuperstructure, diaphragm and anodes, again lowered in position, whenthe cell may again be put into operation. If there is any insolublematerial on the diaphragm, or the anodes require inspection. the hoistis hooked on to the eye-bolts 23, and all the anodes elevated, while,however, the diaphragm remains undisturbed. It the diaphragm needsrepairs, or the anodes re-' overhead hoist or preferably, by a deviceshown at 19,'Figs. 2 and 3, by means of which the turning of a screw, orsimilar device, thelsuperstructure may be elevated frqm day to day orfrom week to week, as the cathode deposit is built up. When the depositis removed, say, at the end of one or two months, the cycle may berepeated. The distance between the anode and diaphragm requires onlyoccasional adjusting, but when necessary it is accomplished through thesuspenders 6 and 18. In this way, all possible adjustments can be made,even while the apparatus is in operation.

, Circulation of the electrolyte is desirable, especially the anolyte,if that has in suspension insoluble, disintegrated, or non-adherentanode material. In this way the insoluble matter may be removed insuspension from the electrolyzer, settled out in the settling tanks 29and 30, and the respective solutions returnedto the apparatus by meansof pumps 25 and 26. In returning the solutions, they may be first givena preliminary treatment in the towers 14 and 15 to facilitate the,electrolysis when introduced into the cell. A treatment with sulfurdioxid is especially desirable in the electrolysis of .impure coppersolutions, as the gas-reduces the required electromotive force in thecell, increases the acid regeneration, decreases the anodedisintegration, and by reducing the bivalent salts "to the univalentcondition increases the efiiciency of deposition.

If gases are released during electrolysis which are injurious to thehealth of the attendants, or which it.is desired to use, such as oxygen,ozone, or chlorin, it is desirable to hood the anode bell, as shown inFig. 4; in which case, the anodes are preferably 0s.- c1llated with theanode bell and diaphragm,

instead of being stationary, as shown in Fig. 1. The gases ma be removedfrom the hood through the flexible tubing 34. If it is desired tointroduce into the hood another gas to combine with the gas releasedduring electrolysis, tlli's may be admitted through a similar tubing 35,and allowed to flow through the hood. Similarly if a gas is to bestrengthened or re-standardized, for use outside of the electrolyzer,the partially exhausted gas may be introducedinto the hood throughtubing 35 and withdrawn through tubing 34. The rate of flow through thehood may be regulated according to the strength of gas required.

In the electrolysis of impure copper solutions, especially at highcurrent densities,

it is quite possible to deposit the copperas r a fine sponge and removeit automatically from the cell. -It may then be settled out from theelectrolyte in the settler 29 or 30, and the electrolyte returned to theelectro lyzer.

While the apparatus has'been particularly described with the anodesuspended within the electrolyte bell, occasion may require that theelectrodes be reversed, and the cathode placed in the electrode bell.This may be quite desirable, or even necessary 1n some of cross-piecesat suitable distances apart,

which, while supporting the fabric 46, also acts as. an efficientagitator of both the anolyteand catholyte. The cross-pieces arepreferably at least as close together as the amplitude of oscillation,so that if any uneven building up of the cathode occurs they will act aseveners and prevent the deposit from building up excessively in oneplace, or of getting to the diaphragm fabric, and tearing it, if thedeposit is hard. It is desirable, therefore, to have the amplitude ofoscillation as great or greater than the distance apart of the diaphragmcross-pieces. If the deposit is loose, as in the case of sponge copper,these cross-pieces may be arranged similar to the modified top piece 39,so that the deposit may be continuously and automatically removed fromthe cell without interrupting the electrolysis.

In the electrolysis of gold or silver from cyanid solutions obtainedfrom treating ores, a diaphragm may not be necessary, but the diaphragmframe, used as an agitator, is highly desirable, whether the fabric isincluded or not. 1

The difficulties in the electrolysis of cyanid solutions is theirextreme dilution in the precious metals, and the formation'of a scum onthe surface of the mercury cathode. These difiiculties are overcome bythe present invention by the oscillation of the diaphragm whereby largevolumes of solution are brought in contact with the electrodes, and thescum is removed from the surface of the mercury cathode by having abrush or scraper 42, Fig. 5, dip into the surface of the mercury andthus continuously exposing bright and fresh surfaces for the depositionand amalgamation of the precious metals. In the electrolysis of cyanidsolutions resulting from the extraction of gold or silver from theirores, a mercury cathode is preferably used, as indicated by 2 in thedrawings. With the mercury cathodes are preferably used iron anodes. Theprecious metals are deposited into the mercury and form an amalgam,which may be removed at suitable intervals, and Qthe metals recovered bydistilling the mercury, which may then be again used as the cathode. Inthis electrolysis the diaphragm frame may be used with or without thediaphragm fabric memos 46, but it is preferably used to prevent the ironcyanids formed at the anode from getting to the cathode compartment. 01'the iron cyanids may be recovered from the anode compartment andreconverted into the cyanid of the alkali metals for reuse in extractingthe precious metals. Amalgamation "plates, by virtue of the mercurycontained in them, may be regarded as the equivalent mercury in theordinary condition.

If the anode is loose, or composed of pieces or fragments, it may besupported in an independent frame or basket. It will be noted that thephenomenal results obtained by the use of this apparatus are largely dueto the space between the diaphragm and electrodes, and especially tokeeping the anode from immediate contact with the diaphragm. If theanode is oscillated with the diaphragm and in contact with it, myexperiments show that no benefits worth while'are derived by theoscillation. The free circulation of the electrolyte about theelectrodes gives the results sought for.

It is thought that from the full description of the apparatus now giventhat any one skilled in the art will find nodifficulty in applying it toother uses than the ones specifically described.

If zinc sulfate or zinc oxid, for example, are to be electrolyzed, thesalts are placed in immediate contact with the anode so that theregenerated acid'at once combines with the salt and prevents theelectrolyte from becoming impoverished or too highly acid. Similarly,cement copper, copper precipitate or copper matte may be at once refinedwithout first converting it into blister copper.

I claim:

1. In electrolytic apparatus the combination of an oscillating diaphragmhorizontally disposed, and means in connection with said diaphragm forfacilitating the removal of the non-adherent elect-rode particles fromthe electrolyzer.

2. In electrolytic apparatus a horizontal diaphragm interposed betweenhorizontal electrodes and means of imparting to said diaphragm adifi'erential oscillating motion to facilitate the removal of thenon-adherent electrode material from the electrolyzer.

3. In electrolytic apparatus an oscillating diaphragm having adifierential oscillating motion to facilitate the removal of thenonadherent electrode material from the sphere of influence of theelectric current.

4. In electrolytic apparatusrhaving electrodes horizontally disposed, adiaphra m interposedbetween the electrodes; means or oscillating saiddiaphragm from fixed plvotal points, and means in connection with saiddiaphragm for facilitating the removal of the non-adherent electrodeparticles.

5. In electrolytic apparatus having a stationarycathode, a stationaryanode anddiaphragm interposed between the electrodes, means foroscillating said diaphragm, and means in connection with said diaphragmfor facilitating the removal of the non-adherent electrode material fromthe electrolyzer.

6. In electrolytic apparatus the combination of a tank containing theelectrolyte and horizontal cathode; an anode bell containing' theanolyte and horizontal anode; cross-pieces attached to the anode belland interposed between the electrodes, and means for oscillating saidcross-pieces and anode bell from fixed pivotal points. 7

7. In electrolytic appai atus the combination of an electrolyte tankcontaining the cathode; an anode bell suspended within theelectrolytetank and containing the anode; cross-pieces attached to the bottom ofthe anode bell; means to agitate the cross pieces and the bell, andbrushes attached to the cross-pieces to facilitate the removal of thenon-adherent electrode material.

8. In electrolytic apparatus the combination of a tank containing theelectrolyte and horizontal cathode; an anode bell suspended within theelectrolyte tank; an anode suspended within the anode bell independentlyof theanode bell; cross-pieces arranged at the bottom of the anode belland shaped so as to facilitate the progressive movement of thenon-adherent electrode material, and means for oscillating 'the anodebell. v

I 9. In electrolytic apparatus the combination of a tank containing theelectrolyte and horizontal cathode; an anode bell suspended within theelectrolyte tank and capable of oscillating; a stationary anodesuspended within the electrolyte and anode bell and independently of theanode bell; crosspieces attached to the bottom of the anode bell to actas agitators, and means for oscillating the anode bell from fixedpivotal points.

10. In electrolytic apparatus having an anode bell suspended within theelectrolyte tank, cross pieces attached to the anode bell and shaped soas to facilitate the progressive movement one way of the non-adherentelectrode material.

11. In electrolytic apparatus having horizontal electrodes andoscillating cross-pieces interposed between the electrodes, crosspiecesso disposed that they will be at least as close together as theamplitude of oscillation.

'12. In electrolytic apparatus the combination of a tank containing thecatholyte and horizontal cathode; a horizontal and stationary anodesuspended within the cathode tank; an agitator interposed between theelectrodes and suspended from fixed pivotal points, and means foroscillating sa1d agitator,

13. In electrolytic apparatus havinghorizontal' electrodes, a diaphragminterposed between the electrodes; means for oscillating said diaphragmfrom fixed pivotal points;

.means of facilitating the removal of the insoluble products ofelectrolysis from the electrodes, and means for facilitating thelrremoval from the electrolyzer.

I electrolysis from the electrodes, and means in connection with saiddiaphragm for facilitating their removal from the sphere of influence ofthe electrolysis.

15. In electrolytic apparatus the combination of an electrolyte tankcontaining the electrolyte and one electrode; an electrolyte bellsuspended within the electrolyte tank and containing the oppositeelectrode; a diaphragm interposed between the electrodes; means formoving said diaphragm; means of simultaneously passing a direct and analternating current through the electrodes.

16. In electrolytic apparatus the combination of an electrolyte tankcontaining the electrolyte and an electrode; an electrolyte bellsuspended within the electrolyte tank and containing the oppositeelectrode; a diaphragm interposed between the electrodes; means formoving said diaphragm; means of simultaneously passing a direct and. analternating current through the electrodes, and means for removing thenon-adherent electrode material from the sphere of influence of theelectrolysis.

l7.-In electrolytic apparatus the combi- 'nation of an electrolyte tankcontaining the electrolyte and an electrode; an anode bell suspendedwithin the electrolyte tank and containing the opposite electrode; :1diaphragm interposed between the electrodes; means of introducing intothe electrolyte a reagent; means for oscillating the diaphragm, andmeans in connection with said diaphragm for facilitating the removal ofthe insoluble non-adherent electrode material from the sphere ofinfluence of the electrolysis.

18. In electrolytic apparatus the combination of an electrolyte tankcontaining the electrolyte and an electrode; an anode bell suspendedwithin the electrolyte tank and containing the opposite electrode; adiaphragm interposed between the electrodes and arranged to facilitatethe progressive movement of the non-adherent electrode material andremoving it from the electrolyzer, means for separating the non-adherentinsoluble electrode material from the electrolyte, and means forreturning the clarified electrolyte to the electrolyzer.

19. In electrolytic apparatus the combination of a tam: containing theelectrolyte and horizontal electrodes; a diaphragm composed of a fabricsupported by a suitable frame work interposed between the electrodes;means in connection with the diaphragm for the escape of gases from theunder side of the fabric; means for facilitating the removal of theinsoluble nonadherent electrode material from the electrodes; means formoving said diaphragm, and means in connection with said diaphragm forfacilitating the progressive movement one way of the non-adherentelectrode material.

20. In electrolytic apparatus having stationary electrodes, .anoscillating diaphragm arranged to catch the insoluble non-adherentelectrode material and continuously reinove it from the sphere of theelectrolysis.

21. In electrolytic apparatus the combination of a tank containing theelectrolyte and stationary cathode; an anode bell suspended within theelectrolyte tank; a stationary anode suspended within the anode bell andindependently of it; a diaphragm interposed between the electrodes andattached to the anode bell; means of adjusting the vertical distancebetween the diaphragm and cathode; means for adjusting the verticaldistance between the diaphragm and anode, and means for oscillating thediaphragm and anode bell.

22. In electrolytic apparatus a stationary anode; a stationary cathode;a diaphragm interposed between the electrodes; means of moving saiddiaphragm; means for adjusting the vertical distance between the cathodeand diaphragm; means for adjusting the vertical distance between thediaphragm and anode, and means for simultaneously removing the diaphragmand one electrode from the electrolyte tank.

23. In electrolytic apparatus a stationary anode; a stationary cathode;a diaphra m interposed between the electrodes; means for adjusting thevertical distance between the cathode and diaphragm; means for adjustingthe vertical distance between the anode and dia hragm, and means foroscillating the diaphragm from fixed pivotal points.

24. In electrolytic apparatus a stationary anode; a stationary cathode;a diaphragm interposedbetween the electrodes and suspended trom fixedpivotal points; means for adjusting the vertical distance between thediaphragm and cathode; means for adjusting the vertical distance betweenthe diaphragm and anode; means for oscillating the diaphragm, and meansof simultaneously removing the diaphragni and one electrode from theelectrolyte tank.

25. In electrolytic apparatus the combination of an electrolyte tankcontaining the electrolyte and a horizontal electrode of one memos sign;a stationary horizontal electrode of the opposite sign suspended withinthe electrolyte tank and substantially horizontal with the otherelectrode; cross-pieces interposed between the electrodes and suspendedindependently of the electrodes; and means for oscillating saidcross-pieces, thereby. simultaneously agitating the electrolyte incontact with both electrodes.

26. In electrolytic apparatushaving electrodes horizontally disposed, amercury cathode, an agitator interposed between the electrodes, andmeans in connection with said agitator for removing any undesirable scumfrom the surface of the cathodewhich may interfere with satisfactoryelectrolysis.

27. In electrolytic apparatus having electrodes horizontally disposed, amercury cathode, an agitator interposed between the electrodes, andmeans in connection with said agitator l'or maintaining the surface ofthe mercury in a condition to facilitate the amalgamation of thedeposited metals in the mercury, and means for oscillating saidagitator.

28. In electrolytic apparatus having elec trodes horizontally disposed,cross-pieces interposed between the electrodes and supported bysuspenders oscillating between the anode and sides of the electrolytetank, and means for oscillating said cross-pieces independently of theelectrodes.

29. In electrolytic apparatus a horizontal mercury cathode, a perforatedand horizontal anode substantially parallel to the cathode, an agitatorinterposed between the electrodes and supported by suspenders passingbetween the anode and sides of the electrolyte tank, and means foroscillating the agitator and suspenders.

30. In electrolytic apparatus having elecsides of the electrolyte tank,and means for moving said agitator relatively to the electrodes.

32. In electrolytic apparatus an electrolyte tank containing astationary horizontal cathode, a stationary anode substantially parallelto the cathode suspended within the electrolyte tank and arranged toallow a space between the edges of the anode and sides of theelectrolyte tank, an agitator interposed between the electrodes andsuspended independently of the electrodes by supports passing betweenthe edges of the anode and sides of the electrolyte tank, and means formoving said agitator independently of the electrodes.

33. In electrolytic apparatus having electrodes horizontally disposed,an agitator interposed between the electrodes and suspended by supportspassing between one of the electrodes and sides of the electrolyte tank,and means for moving said agitator independently of the electrodes.

WILLIAM E. GREENAWAIJTD Witnesses:

THOMAS WALTEMEYEIR, J. S. Hnannr.

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